DMVPN using loopback interface vs. physical interface

[ernesto_tello]

In a DMVPN,what´s the difference between using a loopback interface as a tunnel source instead of a physical interface?

[joe19366]

it will work as long as the loopback has a public ip that is routed in and out the real "internet" facing ip.

it would technically *could* work if you had a private IP on the loopback and some really good nat rules - but that is a good lab experiment i have never tried :) wonder what NHRP cache would do there... hmmmm....

:)

[Nick Cutting]

It will work for a static one to one nat. PAT doesnt play well with GRE because ports dont exist in GRE (not sure if NAT traversal can help here like it does with ISAKMP - it works on spokes) You also need to make sure that the loopback is set to work with the crypto profile.  Joe is right, the address it terminates on is best to be Public address space that you own, that is multihomed - if this is a hub.